Insulating films and protective films for use in electronic devices such as ICs, LSIs and liquid crystal devices are required to have a heat resistance to a temperature of 300° C. or higher because temperature sometimes rise up higher during the process for manufacturing device. While ceramic-type films such as Spin On Glass (SOG) films have been conventionally used for such insulating films and protective films, use of organic polymers has been developed in recent years from the viewpoints of further improvements in insulating property and lowering of dielectric.
Polybenzimidazole and polypyromellitimide, for example, are excellent in heat resistance but are soluble only in strong acids such as concentrated sulfuric acid and hence cannot be used as protective films for plastics and metals.
Polyimides have high water absorption property and hence have a problem that the strength of adhesion to substrates week.
Accordingly, it is an object of the present invention to provide a heat-resistant polyether having a heat resistance to a temperature of 300° C. or higher, sufficient solubility in solvent, low water absorption and high adhesion to substrates such as silicone wafer.